Grinding apparatus



Jan. 28, 1964 Filed March 28, 1962 A. BARICORDI GRINDING APPARATUS 2 Sheets-Sheet 1 INVENTOR. A, Bardco rc/d Jan. 28, 1964 A. BARICORDI 3,119,569

GRINDING APPARATUS Filed March 28, 1962 2 Sheets-Sheet 2 INVENTOR. A BcL/LCcNc/L United States Patent 3,119,569 GRINDING APPARATUS Antonio Baricordi, Via Cantonale 20, Lugano, Switzerland Filed Mar. 28, 1962., Ser. No. 183,172 8 Claims. (Cl. 241-55) This invention relates to a grinding apparatus and refers more particularly to a grinding apparatus having a substantially cylindrical grinding space containing radially extending grinding chambers.

Grinding devices which are used in numerous industrial processes for comminuting raw or technically produced substances can be conveniently classified in accordance with their suitability for coarse, medium-size, fine or superfine grinding, while the structural properties of the material provide a further classification into hard, mediumhard and soft grinding. The type of grinding is characterized by the physical forces which act during the grinding process, and these forces can be divided into compressive forces, shearing forces, frictional forces, impact forces and projection forces. As a rule, two of the abovernentioned types of forces are combined in one grinding apparatus. Exceptions are the jaw crusher which uses substantially only the compressive forces and the so-called millstones wherein compressive, shearing and frictional forces are used jointly.

A suggestion has been made to utilize sudden drops in pressure for grinding purposes, for example, by introducing a gas under high pressure into the material to be comminuted. Such suggestions have not reached the stage of practical'utilization.

The extent of comminution is an important factor in all grinding processes, this being the ratio of the coarsest particle of the material to be ground to the coarsest particle of the material after grinding. This ratio has certain practical limits which are set by the type of the machine and the forces which are being used.

An object of the present invention is to improve prior art grinding apparatus.

Other objects will become apparent in the course of the following specification.

In accordance with the present invention substantially all known physical effects are exerted jointly upon the substance being ground to produce a grinding having very high cornminution ratios. The grinding space of the apparatus of the present invention is generally divided into convex and concave grinding chambers which extend radially outwardly from a central shaft.

Thus the present invention provides a combination of all known physical types of grinding in a continuous operation in a single apparatus, with the result that a high comminution ratio is attained and that there is an exceptionally high grinding effect upon treated substances of all structural ranges from a hard substance to a soft one.

The invention will appear more clearly from the following detailed description when taken in connection with the accompanying drawing showing, by way of example, preferred embodiments of the inventive idea.

In the drawings:

FIGURE 1 is a vertical sectional view of a grinding apparatus of the present invention.

FIGURE 2 is a section along the lines IIII of FIG. 1.

FIGURE 3 is partly a side view of and partly a section Patented Jan. 28, 1964 "ice through a somewhat differently constructed grinding apparatus having a side inlet.

FIGURE 4 is a detail view of a somewhat different construction showing a part of a convex grinding chamber with an air jet producing member located at the outer end of the chamber.

FIGURES 5, 7, 9 and 11 are side views of air vortex producing members.

FIGURES 6, 8, 10, and 12 are end views of the members shown in FIGS. 5, =7, -'9 and 1-1, respectively.

FIGURE 13 is a fragmentary view illustrating the arrangernent of holes in the walls of a grinding arm.

FIGURE 14 is a fragmentary view illustrating the arrangement of holes in the wave-like wall enclosing the grinding space.

FIGURE 15 is a section along the line XVXV of FIG. 14.

FEGURE 1 shows that an apparatus embodying the principle of the present invention includes conducting, mixing and grinding arms 4 and 5 which are mounted upon a shaft 1 by means of an attachment ring 2 and connecting members 3. The arms 4 and 5 are mounted in pairs upon the shaft 1 and are curved, the arrangement being such that an inner grinding chamber 6 having in section the outline of a bi-convex bottle is formed between the convexly curved arms 4, 5 of each pair, while grinding chambers 7 of bi-concave outline are located between two adjacent pairs of arms 4, 5. 7

As shown in FIG. 2, the grinding arms are provided with holes, at least in the central parts of the arms, the arrangement being such that holes 9 which are preferably elongated in shape, are located around a central hole -8, the longitudinal axes 10 of the holes 9 forming angles of 45 degrees each with the central axis 11 of the hole 8.

Each of the grinding arms 4, 5 carries a reinforcing member 12 which can be made of a particularly wearresistant material.

The number of pairs of arms 4, 5 upon the rotor of the grinding apparatus may be an even or an uneven one. However, it was found preferable to provide an uneven number of pairs of arms.

All grinding arms 4, 5 are held together at their side edges by holding rings 13.

The rotor of the apparatus,,which consists of the shaft 1, the attachment ring 2, the arms 4, 5, their reinforcing members 12 and the holding rings 13, is enclosed by a stator having a wall 14 which is preferably of wave-like form, the axes of the waves extending parallel to the shaft 1.. Those portions 15 of the waves which are directed toward the inner grinding space, are provided with holes disposed around a central hole 16, as shown in FIG. 14. The central hole 16 is slit-like in shape and the main axis 17 of the hole 16 extends coaxially to the direction of rotation of the rotor. The holes 18, 18a, 19 and 1% which are located around the central hole 16, are also elongated and their longitudinal axes 20 form angles of about degrees with the axis 17.

FIGURES 5 to 12 show air-whirl producing members 21 and 21a creating special air whirl bundles which are guided in the form of jets and add a grinding effect by means of aid whirl jets to the above-mentioned types of grinding.

Whenever the nature of the substance to be ground makes this advisable, air whirls, air jets and air whirl a bundles of this type may be produced in the concave chambers 7 as well as in the convex chambers 6. In that case the members 21 are so mounted upon the arms adjacent the reinforcing members 12 that they project into the concave grinding chambers 7, while the grinders 21a are mounted upon arms 4 in a similar manner and at substantially the same distance from the shaft 1 within the convex grinding chambers 6 (FIG. 1).

The construction of the jet-producing members 21 and 21a is such that an exceptionally large number of variations may be attained.

FIGURES 5 and 6 show jet-producing members provided-with webs [1 located between spaces a which extend radially outwardly. If the particles of the substance to in suspension by an air current, the mixture of air and particles willproject the particles against the stator wall 14, acting as an impact grinder. The particles are then subjected to impact and shearing effects.

However, the same members 21 may be arranged in the manner shownin FIGURES 7 and 8. Then a typical whirl effect at the edges isproduced as the result of which thevery fine particles which are subjected to a powerful stripping effect, are conducted into the interior of the grinding chambers and are kept away from the reinforcing members 12 which are exposed to the greatest wear and tear.

If the arrangement shown in FIGURES 9 and 10 is selected, a centrally directed jet is produced, which is directed toward the middle of the reinforcing members 12 and which produces a very concentrated impact effect within a limited space.

The arrangement shown in FIGURES 11 and 12 is such that outwardly directed currents of the particles to be ground are divided into numerous small separate air whirl jets, with the result that extremely fine grinding is attained.

In'the construction shown in FIG. 1 spaces are provided between the jet-producing members and the adjacent arms.

However, according to the construction of FIG. 4, the members 21a are so large that they close the space between the grinding arms, so that with the exception of the passages for the air whirl jets, no other radial opening is provided in the grinding chamber.

The jet-producing member 21 may be so constructed 'that FIGURES 5, 7, 9 and 11 will illustrate the four differerit sides ofthe same member, the member being turned progressively to the extent of 90 degrees.

However, opposed sides or several sides of the same member may have the same form, which is one of those illustrated inFIGURES 5, 7, 9 and 11.

The grinding operations of the described apparatus are extremely varied:

In the construction shown in FIG. 1, the material to be ground is supplied circumferentially to the apparatus in the direction of the arrow C.

In that case the grinding chambers can be closed from the sides by walls (not shown) rotating along with the grinding chambers.

However, the material to be ground can be also introduced sidewise into the apparatus, as indicated by the arrow D in the construction shown in FIG. 3.

The material to be ground enters into the rotating grinding chambers and becomes highly turbulent therein. The grinding takes place partly by direct impact of the particles with the grinding arms 4, 5 and with the edges of the holes 8, 9 in the arms, whereby the particles are broken up by impact against the numerous edges of the holes; immediately thereafter some or most of the particles are subjected to air whirls and whirl jets which rub one against the other and thus introduce a further grinding effect which is described in the art as autogenous grinding. Finally, the jet producing members 21, 21a cause the floating material to be projected in the form l} of jets or sprays against the immovable surfaces of the stator. The material which has not been subjected to impact with the arms 4, 5 or to the cutting action of the holes 9, it) in these arms will be projected outwardly by rotational forces and will be subjected to shearing and impact effects, which are automatically produced by the sliding of the reinforcing members 12 past the wave-like depressions of the wall 14 and by the shape of the holes 16, 13, 18a, 19 and 19a with which this wall are provided. Only those particles the largest diameter of which is smaller than the smallestdiameter of these holes, pass through the stator wall 14 and drop by gravity and through downwardly directed air whirls as the finished ground product through the space located between the wall 14 and the outer casing 23.

The apparatus of the present invention, the grinding space of which is divided into convex and concave radially outwardly extending grinding chambers, combines substantially all known physical grinding effects, namely,

pressure-exerting forces, shearing forces, frictional forces (autogenous grinding), impact forces, projection forces and forces resulting from varying air jets and air whirls. The grinding output of this apparatus is characterized by an exceptionally high degree of comminution and the apparatus has a wide range of application as far as the various substances to be ground are concerned.

It is apparent that the examples described above have been given solely by way of illustration and not by way of limitation and that they are subject to many variations and modifications within the scope of the presentinvention. All such variations and modifications are to be included within the scope of the present invention.

What is claimed is:

l. A grinding apparatus, comprising a central shaft, means forming a substantially cylindrical space enclosing said shaft, and a plurality of arms carried by said shaft and extending radially into said space, said arms being shaped to form outwardly extending biconvex and biconcave grinding chambers, the central portions of said arms being provided with holes.

2. An apparatus in accordance with claim 1, wherein the holes of each arm comprise a central hole and elongated holes disposed around the central hole and forming angles therewith of substantially 45 degrees.

3. A grinding apparatus, comprising a central shaft, means forming a substantially cylindrical space enclosing said shaft, a plurality of arms carried by said shaft and extending radially into said space, said arms being shaped to form outwardly extending biconvex and biconcave grinding chambers, the central portions of said arms being provided with holes, and air jet-producing members carried by the outer ends of said arms adjacent the outer ends of said grinding chambers to form jets projecting into said chambers.

4. An apparatus in accordance with claim 3, wherein said air jet-producing members have channels forming radially extending central jets.

5. An apparatus in accordance with claim 3, wherein said air jet-pr0ducing members have channels forming radially extending wide-surfaced jets.

6. An apparatus in accordance with claim 5, wherein said wide-surfaced jets are concentrated in the central portions of said chambers.

7. A grinding apparatus, comprising a rotor having a central shaft and a plurality of arms carried by said shaft, said arms having rounded curved portions forming outwardly extending biconvex and biconcave grinding chambers and having holes; and a substantially cylindrical stator enclosing said rotor and having a wave-shaped wall, the axes of the waves of said wall extending parallel to said shaft, said waves have portions extending inwardly toward said shaft, said portions having holes.

8. An apparatus in accordance with claim 7, wherein each of said wave portions has a central elongated hole,

the axis of said central hole extending coaxially to the direction of rotation of said rotor, and elongated holes disposed around said central hole and having axes forming angles of substantially 90 degrees with the axis of said central hole.

References @itezl in the file of this patent UNITED STATES PATENTS 379,943 Earnes Mar. 27, 1888 6 Sanford Oct. 28, 1924 Crowe May 1, 1928 Mac Gregor Jan. 30, 1934 Seckendorlf Apr. 28, 1936 Lykken Dec. 8, 1942 FOREIGN PATENTS Germany Apr. 6, 1961 

3. A GRINDING APPARATUS, COMPRISING A CENTRAL SHAFT, MEANS FORMING A SUBSTANTIALLY CYLINDRICAL SPACE ENCLOSING SAID SHAFT, A PLURALITY OF ARMS CARRIED BY SAID SHAFT AND EXTENDING RADIALLY INTO SAID SPACE, SAID ARMS BEING SHAPED TO FORM OUTWARDLY EXTENDING BICONVEX AND BICONCAVE GRINDING CHAMBERS, THE CENTRAL PORTIONS OF SAID ARMS BEING PROVIDED WITH HOLES, AND AIR JET-PRODUCING MEMBERS CARRIED BY THE OUTER ENDS OF SAID ARMS ADJACENT THE OUTER ENDS OF SAID GRINDING CHAMBERS TO FORM JETS PROJECTING INTO SAID CHAMBERS. 